1. Field of the Invention
This invention relates to a disposable safety syringe having a double ended hypodermic needle cannula which is engaged by a set of jaws and releasably retained at the distal bore of a syringe cylinder, and to means associated with a piston assembly for releasing the cannula from its engagement at the distal bore and retracting said cannula completely within the cylinder to form a compact package that is suitable for handling and disposal.
2. Background Art
Hypodermic syringes are used for a variety of injection procedures including the delivery of medicinal drugs to a recipient. However, once the injection procedure is completed and the syringe cylinder emptied, problems may arise as a consequence of failing to properly and adequately dispose of the syringe. By way of the first example, the syringe may be used to treat a patient having a communicable disease. To prevent reuse, the hypodermic needle is sometimes broken before the syringe is discarded. Health care workers are susceptable to accidental and potentially infectious needle sticks due to the careless handling of the hypodermic needle when breaking the needle or disposing of the syringe after use. The resulting mini-accidents caused by an accidental needle stick typically requires a blood test for such diseases as AIDS and hepatitis. The corresponding cost and inefficiency of testing health care workers who have received an inadvertent needle stick result in considerable waste, which may be particularly damaging to a health care facility striving for economy and efficiency. By way of a second example, drug abusers have been known to rummage through the trash of a health care facility in an effort to find empty syringes which have been discarded after use. Such syringes are often used in an illicit capacity, whereby to promote drug abuse and the possible spread of disease.
One example of a syringe having a hypodermic needle cannula that may be retracted within a cylinder and canted relative to the longitudinal axis of said cylinder is available by referring to U.S. Pat. No. 4,804,370 issued Feb. 14, 1988 and assigned to the assignee of this patent application.
One example of a syringe having a hypodermic needle cannula that is releasably retained at the distal bore of the syringe cylinder by a set of jaws is available by referring to U.S. Pat. No. 4,808,169 issued Jan. 28, 1989 and assigned to the assignee of this patent application.